Trailer heating system

ABSTRACT

A central heating system for the enclosed space of a vehicle trailer, or motor home having circulating liquid medium which is heated in a boiler and heat transferred to radiators in an open system via an expansion vessel. The expansion vessel is situated at a high level and is so constructed that vapor in the riser conduit of the system is condensed and substantially only liquid descends in the downward conduit from the expansion vessel; the heating of the enclosed space is controlled by a thermostat operatively connected to the system.

United States, Patent 91 Hagdorn et al. I I

[451 Feb. 26, 1974 i 41 TRAILER HEATING SYSTEM [75] Inventors: Manfred Otto Hagdorn, Stockholm;

Torsten Palmeth, Sollentuna; Jean lvan Ragnar Boivie,'Stockholm, all of Sweden 73 Assignee: Aktiebolaget Electrolux, Stockholm,

Sweden 22 Filed: Aug. 16,1972 21 Appl. No: 281,048

[30] Foreign Application Priority Data Aug. 20, 197i Sweden 10578/71 [52] us. Cl. 237/59a237/66 511 int.- cr..........; F24d 3/10 58 Field! of Search 237/8 A, s R, 66, 59

[ 56] References Cited UNITED STATES PATENTS 1,732,505 10/1929 Dawson 237/66 370,897 10/1887 Searle 237/66 253,389 2/l882 Johnson 237/66 Primary Examiner-William E. Wayner Attorney, Agent, or Firm-Alfred E. Miller 57] ABSTRACT 1-5 Claims, 6 Drawing Figures TRAILER HEATING SYSTEM BACKGROUND OF THE INVENTION Heating systems for homes, or the like, are known that use circulating water as the medium. These systems, which are open, employ an expansion vessel located at a high level in the system. Thus, water is heated in a boiler forming .hot water which flows from the heating place in the boiler upwardly to an expansion vessel, and the water in the vessel is circulated downwardly to be cooled by radiators. Since the upward flowing column is hot water and the downward flowing column is relatively colder water, there is a difference in density of the water columns sufficient to achieve continual circulation of the water in the system. However, in heating systems of this type, it is a desired objective to avoid the generation of vapor in the boiler since the generated vapor could not be used for heating purposes but would be cooled off in the expansion vessel that normally is located in an uninsulated attic. Nevertheless, vapor is essential in theascending line of the system in order to'maintain an effective circulation' of the medium transferring heat from the boiler to the radiators.

For the heating of a room or other enclosure it is desirable to place the radiators as-close to the floor of the room as possible. On the other hand, the circulating heating system requires two vertical liquid columns. Thus, in the proposed heating system, there would be a vertical liquid column heated by the boiler, a horizontal liquid flow and another vertical descending liquid column. This latter liquid column would not be cooled since the radiators would be positioned in a horizontal plane. Consequently, the two vertical liquid columns would be approximately the same temperature and the circulation of the heating medium would be negligible. In order to cool the second vertical column in this system, radiators have to be placed at a selected height above the lower horizontal connecting part of the system. This system causes difficulty with the efficient arrangement of the radiators in the space to be heated, and therefore a central heating system with motordriven pumps that ensure an efficient circulation of liquid in the system has been substituted for the first described system. 1

Currently there is an increasing need for central heating systems for rooms or enclosures that eliminate the necessity for driven pumps and thereby reduce the need for their maintenance and service. This is especially true for trailers, small boats and cabins where there is little or no electricity available, and it is desired to heat up the enclosure fast and adjust or control the heat transfer in the enclosure depending upon the heat requirements. In the past, a system has been utilized which eliminates the driving means for circulating liquid. This system is the impulse pump arrangement that is driven by the heat supply only. Since the pumping is dependent upon vapor generation, the liquid level periodically moves up and down in a boiler. Therefore, the pump operates with a pulsating rhythm which corresponds to the movements of the liquid level in the boiler. A serious disadvantage of this system is the considerable throbbing noise created by the pulsating operation of the pump.

SUMMARY OF THE INVENTION the system.

It is an object of the present invention to provide a trailer heating system located between the floor and ceiling of a room that has an effective circulation of the water medium, and a heat transfer to the radiators situated close to the floor of the trailer. I

It is another object of the present invention to provide a novel construction resulting in a fast and smooth start up of a cold system.

Another object of the present invention is to provide a thermostatically controlled valve for adjusting the heating of the trailer.

A further object of the present invention is to provide a central heating system which does not require electrical power, and is provided with a burner which can operate on gaseous or liquid fuel.

Another object of the present invention is to provide an expansion vessel which is so constructed that substantially only liquid appears on the downwards side of the heating system.

An object of the present invention is to provide a relative compact heating system that has an effective air intake arrangement.

The invention will now be more fully described with reference to the accompanying drawings wherein:

FIG. I is a perspective view of the central heating system mounted in a trailer and embodying the principles of our invention. I

FIG. 2 is a perspective view of the central unit of our novel heating system drawn on a larger scale and with parts of the trailer and screen wall cut away for purposes of clarity.

FIG. 3 is a vertical sectional view taken through the trailer and through part of the central unit of the. heating system.

FIG. 4 is a perspective view on a larger scale of the expansion vessel with condenser having parts thereof cut away for purposes of clarity.

FIG. 5 is a side elevational view of certain details of construction of a thennostatically controlled valve arrangement of our present invention, and

FIG. 6 is a fragmentary view of parts like those shown in FIGS. 2, 3, and 4, illustrating another embodiment of the invention.

PREFERRED EMBODIMENT OF THE INVENTION FIG. 1 of the drawings shows a trailer 10 drawn schematically and supported by wheels 11 mounted on a single axle. For purposes of clarity, all of the usual fixtures of the trailer have been omitted in order to illustrate our novel central heating system. The heating system comprises a heat supply and liquid circulating unit referred to generally by the numeral 12- and a conduit 17 which circulates the liquid heating medium through a circuit close to the trailer floor 18 and at the periphery thereof adjacent to the trailer walls 21 and 22 having windows 19 and 20 and a door 23. It should be understood that the other side and front wall of the trailer have been omitted for purposes of this illustration. As seen in FIG. 1, a series of radiators 13, 14, 15, and 16 are appropriately spaced and close to respective walls of the trailer 10.

Referring nowto FIGS. 2 and 3, the heating system embodying our invention is provided with a burner 24 located close to the floor 18 of the trailer 10 and which uses a fuel such as LP gas or a liquid fuel, for example kerosene or oil. The burner 24 shown in FIGS. 2 and 3 is housed in an enclosure 25 which also houses means, such as control devices, and other fittings for the burner 24. The aforesaid meansconstitutes a knob 28 which controls the gas supply and opens a by-pass valve (not shown) in the gas conduit 24a when it is desired to light the burner. In-connection with the latter, the burner 24 can be lit by means of a push button 29 for a piezoelectric lighter (not shown). The enclosure 25 is also provided with a sight window 26 for observing the operation of the flame 27 of the burner 24. As seen in FIG. 3 the enclosure 25 is provided with the opening 25a to which is connected the vertical air intake conduit 30 that extends through an opening 31a in the trailer roof 31. The hot gases generated by the burner 24 are conducted through a flue 32 upwards and through the roof 31 of the trailer 10 and exit through a generally circular top plate 33 which extends in a plane substantially perpendicularto the longitudinal axis of the flue 32. It will be noted that the flue 32 is connected to an opening 32a in the enclosure 25 and passes through an opening 31b in the roof 31. Thus, the hot gases from the burner 24 travel upwards in the flue 32 and laterally under circular plate 33 and out to the atmosphere. The plate 33 has a downwardly projecting annular rim 34 that functions as a protection against rain being swept into the flue 32. The conduit 30 is also provided with a lower, generally circular plate 36 having a downwardly projecting annular rim 35 that formsa protective roof for the air intake of the conduit 30. In addition, an upwardly projecting annular flange 37 is located in the top surface of the roof 31 which functions to prevent water on the root surface from flowing into the air intake conduit 30.

The lower part of the flue 32 is surrounded by a jacket 38 that is filled with a liquid L. This construction forms the boiler for the heating system. A riser pipe 39 is connected to the upper part of the jacket 38 and has the other end thereof connected to an expansion vessel referred to generally by the numeral 40. Referring now to FIG. 4, it will be seen that the expansion vessel 40 has a hose 41 located at the upper part thereof to ventilate the system and to permit vapor to escape to. the atmosphere in the event of an over-pressure in the system. However, the vapor will immediately condense and therefore the hose is connected to the exterior of the trailer 10 by means of a hose extension (not shown) passing through the floor 18 of the trailer 10.

As clearly seen in FIGS. 1 and 3, a down pipe 43 is connected to the conduit 17 through which the liquid in the system is circulated together with the radiators 13, 14, 15, and 16, and which is connected at its other end to the lower part of the jacket 38. At this point, the

- 48 having an inner part 49 which in its lower portion 4 40 includes a lower liquid container 44. Connected into the bottom 44a of container 44 are the riser pipe 39 and the down pipe 43. It is preferable that the liquid container 44 be constructed of a suitable durable transparent plastic material so that the liquid level in the container 44 can be observed. Theupper part of the liquid container 44- is provided with an interior bayonet mount 45 and at the top thereof has a catch 46 for the upper metal sleeve 47, which is fabricated preferably of aluminum. The metal sleeve 47 is retained by a cover has parts 50 fitting into the bayonet mount 45 of the liquid container 44. The inner part 49 and the cover 48 are resiliently connected together by means of a yieldable annular member 51.

The heating system of our present invention is so constructed and arranged that there is an effective liquid circulation inasmuch as the liquid column in riser pipe 39 which comprises the jacket 38 and the riser pipe 39 is hot and contains some vapor. On the other hand, the down pipe 43 contains substantially only hot liquid. Moreover, the conduit 17 through which the liquid medium is circulated extends substantially horizontally close to the floor of the trailer and does not have any significant level differences. Thus, conduit 17 does not influence the flow of the liquid medium therein other than the usual flow resistance of a pipe. This reliquid cooled in the radiators l3, 14, 15, and 16 and in sistance'is overcome by the driving force exerted on the liquid medium producedas a result of the density difference between the two liquid columns in the heat supply and liquid circulating unit 12. It should be apparent that our present construction achieves the. desirable operating condition in which the vapor fonned in the jacket 38 is condensed partly in the liquid in the expansion vessel 40. r

In order to overcome the drawback of previous constructions in which the heat is lost because the vapor in the system passes through an expansion vessel in an uninsulated location, the-heat supply and liquid circulating unit 12 is mounted in a space between the floor 18 and the roof 31 of the trailer 10. As seen in FIG. 3, the rear of the space is provided with a heat insulated wall 52 and the sides by either heat insulated walls 53 (FIG. 2) or by heat. conducting walls such as sheet metal, which are complete or partial, and which conduct some heat to the contiguous ,rooms'of a trailer. This latter construction is of value if, for example,'the contiguous room is used for drying clothes.

Located in the front of the heat supply and liquid circulating unit 12 is a screen 54. An opening 55 is provided in the floor 18 of the trailer through .which cool ambient air flows into the space 56 around unit 12 (FIG. 3). The air is heated by the jacket 38 and the flue 32 and to some extent by the metal sleeve 47 of the expansion vessel .40. This air thus heated flows through the screen wall 54 and into the interior of the trailer 10. It is within the scope of our present invention to make the screen wall 54 removable so that the space 56 and the apparatus therein can be accessible. In addition, it is desirable to make the expansion vessel 40 visible from the interior of the trailer 10 and this is accomplished by the insertion of a window 54a in the screen wall 54 directly in front of the vessel 40. The window 54a permits the liquid level in the transparent expansion vessel to be observed often and maintained at the desired level without removing the screen wall 54.

bealso prepared by knurling.

At thestar t of the heating season, a condition may, v

occur in the present heating system in which the circu-' lation of the liquid medium in the system is delayed in spite of the fact that large amounts of vapor are generated in the boiler. In this condition, the liquid level in the expansion vessel will rise. In order to overcome this condition, a certain part of the exterior surface of the: flue 32 is roughened, as shown at 57. This roughened surface can be produced by sand blasting, metal coating, or the like, and when vapor is generated along the exterior walls of the flue 32 within the jacket 38 small vapor bubbles are caused to leave these walls, especially at the peaks of the roughened surface, which may It is desired to point out that the lower part of flue 32 in the jacket 38 acts as a preheater for the liquid in the: jacket 38 and the upper part5? of the flue 32 within. the jacket 38 functions as a vapor generator. In order: to have the heat of the gases emitted in suitable propor-- tions to the two boiler parts, within the jacket 38, it is desirable to use a flue baffle (not shown) which ensuresi that the main heat quantity is emitted to the vapor generating part 57 of the flue 32. This result can be achieved by means of a pipe suspended in the flue 32 and having a flattened lower end (not shown).

FIG. S shovvs a thermostatically controlled valve ar' rangement for our unit 12 in which a' temperature sen-. sitive bulb 58 is placed in a suitable location in the in-. terior of the trailer 10. The bulb 58 is connected to a non-return valve 42 may be provided in the circulation system. Any known kind of a valve suitable for the purpose may be used and be disposed anywhere in the system. Preferably, however, the valve is placed as shown in FIG. 6, i.e., at the end of the riser pipe 39 inside the container 44.

.What we claim i 1. A central heating arrangement of at least one room of a forming space having a limited height difference between floor and ceiling in an open system having a circulating liquid and radiator means, comprising:

a. a boiler for the liquid, i

'b. means for heating the boiler,

c. an expansion vessel,

d. a riser pipe connecting the boiler to the expansion vessel, v

e adgv r pipe connecting the expansion vessel to the radiatormeans,

the expansion vessel being so constructed and arranged that the vapor ascending together with the liquid in the riser pipe is condensed and passes through the down pipe with its heat content being the form of a condenser.

thermostatically controlled valve 59 mounted in a bypass pipe 60 between portions'of the conduit 17 which short circuits the radiators 13, 14, 15, and 16. Thus, when the interior space in the trailer 10 is too hot as sensed by bulb 58, the valve 59 is opened and most of: the liquid in conduit 17 will flow through by-pass pipe 60 and back to the boiler since the portion of conduit 17 provided with the radiators 'has a large flow resistance and consequently the radiators l3, 14, 15, and 16 will be short-circuited. In addition,'a valve 61 in the gas conduit 24a is also thermostatically controlled by means of a temperature sensitive bulb 62 located in the conduit 17 close to its connection to the bottom of jacket 38. The bulb 62 measures the return liquid tem-; perature and is operatively connected to the valve 61; in order to adjust the gas supply to the burner 24, it being desirable to maintain the liquid temperature at about -7580 centigrade. The foregoing thermostatically controlled valve arrangement has the desirable result of being able to adjust the heat output from the; system-in accordance with the desired heating requirements.

- If the number of steam bubbles generated increases; the difference in specific weight of the upwardly directed riser pipe having liquid plus steam and the downwardly flowing column of liquid becomes greater so that the circulation in the system is speeded up.

At loWheat TripTnYo the Bar 125i ithiiybcciifihafthe liquid circulation is not continuous. To prevent this, av

3. The arrangement in accordance with claim 1 further comprising a flue for the heating means, a jacket surrounding a portion of the flue and forming the boiler }and additionally constituting part of the riser pipe.

4. The arrangement in accordance with claim 3 wherein the height of the boiler forming part of the riser pipe is approximately the same height as the remainder of the riser pipe.

5. The arrangement in accordance with claim 3 further comprising a housing for the burner, the flue being .connected at the intake end to the housing, and an air intake conduit openingv at one end to the exterior of the 'enclosed space and connected at the other end to the housing for supplying combustion air to the burner.

6. .The arrangement in' accordance with claim 3 vwherein the riser pipe is supplied-with heat over at least half its height.

7. The arrangement in accordance with claim 3 wherein the portion of the flue surrounded by the jacket has an upper'part provided'with an exterior surface which is roughened thereby causing vapor bubbles to be emitted from the upper part of the flue portion within the jacket.

8. The arrangement in accordance with claim 7 wherein the roughened surface is knurled.

9. The arrangement in accordance with claim 3 wherein an opening is provided in the floor of the enclosed space through which cool ambient air passes and flows over the boiler, flue, and the expansion vessel and thus becomes heated.

10. The arrangement in accordance with claim 1 wherein a non-return valve is arranged in the liquid circulation system.

11. The arrangement in accordance with claim 10 wherein the non-return valve is mounted inside the liquid container in connection to the riser pipe.

12. A central heating arrangement located between the floor and the ceiling of a space having a liquid heated in a boiler operated by a burner and circulated in radiator means in an open system comprising:

a. an expansion vessel,

b. a riser pipe connecting the boiler to the expansion vessel,

c. a down pipe connecting the expansion vessel to the radiator means,

d. the expansion vessel having one part which is a vapor separator and liquid container and another part which is an air cooled condenser whereby vapor ascending together with the liquid in the riser pipe is condensed and its heat content supplied to the radiator means after passing through the down P p e. the radiator means being positioned at or above the level ofthe burner, and

f. means providing heat c fimunicafionover the expansion vessel and boiler by air flow thereover to t zp tni a.

13. The arrangement in accordance with claim 12 wherein the radiators are located at a lower level than the boiler.

14. The arrangement in accordance with claim 12 wherein the air cooled condenser is a metal sleeve having an inner part and being provided with a cover.

15. The arrangement in accordance with claim 14 further comprising a yieldable element connecting the inner part and thecover.

UNITED STATES PATENT. OFFICE I CERTIFICATE OF CORRECTION 3,-79L+.,242

Eaten't No.

Dated Fr-i rmlv'gw r 1 74 I MANFRRT) no m-mommy mmzsmm Tammi? mmrvm i'il.

It is certified p haterror 'a ppears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

line 9, cancel "forming".

Column 6,

Column. 6, line 24, n l 11 11 C0lumn6; 1 inef2 5, change "said" to ---.the---- Column 6, line 25, change "radiators" to ---radiatox mea -H ColwnnB, line QichangflradiatOrs are to -radietor means is;

Signed and Sealed this 17th day of September. 1974,

. (SEAL) Attest:

MCCOY M. GIBSON JP cc MARSHALL DANN Attesting Officer Commissioner of Patents ZURM egg-1050 (19-59) USCOMM-DC scan-Poo I w fi lLS. GOVERNMENT PRINTING OFFICE: Hi9 O-JEE-SSL 

1. A central heating arrangement of a room forming an enclosed space having a limited height difference between floor and ceiling in an open system having a circulating liquid and radiators comprising: a. a boiler for the liquid, b. means for heating the boiler, c. an expansion vessel, d. a riser pipe connecting the boiler to the expansion vessel, e. a down pipe connecting the expansion vessel to the radiators, f. the expansion vessel being so constructed and arranged that the vapor ascending together with the liquid in the riser pipe is condensed and passes through the down pipe with its heat content being supplied to the radiators with the liquid, and g. said boiler, radiators, and expansion vessel all being located within said enclosed space and h. means providing heat communication over the expansion vessel and boiler by air flow thereover to said room.
 2. The arrangement in accordance with claim 1 wherein the expansion vessel has part thereof in the form of a vapor separator and another part thereof in the form of a condenser.
 3. The arrangement in accordance with claim 1 further comprising a flue for the heating means, a jacket surrounding a portion of the flue and forming the boiler and additionally constituting part of the riser pipe.
 4. The arrangement in accordance with claim 3 wherein the height of the boiler forming part of the riser pipe is approximately tHe same height as the remainder of the riser pipe.
 5. The arrangement in accordance with claim 3 further comprising a housing for the burner, the flue being connected at the intake end to the housing, and an air intake conduit opening at one end to the exterior of the enclosed space and connected at the other end to the housing for supplying combustion air to the burner.
 6. The arrangement in accordance with claim 3 wherein the riser pipe is supplied with heat over at least half its height.
 7. The arrangement in accordance with claim 3 wherein the portion of the flue surrounded by the jacket has an upper part provided with an exterior surface which is roughened thereby causing vapor bubbles to be emitted from the upper part of the flue portion within the jacket.
 8. The arrangement in accordance with claim 7 wherein the roughened surface is knurled.
 9. The arrangement in accordance with claim 3 wherein an opening is provided in the floor of the enclosed space through which cool ambient air passes and flows over the boiler, flue, and the expansion vessel and thus becomes heated.
 10. The arrangement in accordance with claim 1 wherein a non-return valve is arranged in the liquid circulation system.
 11. The arrangement in accordance with claim 10 wherein the non-return valve is mounted inside the liquid container in connection to the riser pipe.
 12. A central heating arrangement located between the floor and the ceiling of an enclosed space having a liquid heated in a boiler operated by a burner and circulated in radiators in an open system comprising: a. an expansion vessel, b. a riser pipe connecting the boiler to the expansion vessel, c. a down pipe connecting the expansion vessel to the radiators, d. the expansion vessel having one part which is a vapor separator and liquid container and another part which is an air cooled condenser whereby vapor ascending together with the liquid in the riser pipe is condensed and its heat content supplied to the radiators after passing through the down pipe, and e. said radiators being positioned at or above the level of said burner, and f. means providing heat communication over the expansion vessel and boiler by air flow thereover to said room.
 13. The arrangement in accordance with claim 12 wherein the radiators are located at a lower level than the boiler.
 14. The arrangement in accordance with claim 12 wherein the air cooled condenser is a metal sleeve having an inner part and being provided with a cover.
 15. The arrangement in accordance with claim 14 further comprising a yieldable element connecting the inner part and the cover. 